Lecture 25 and 26
Lecture 25 and 26 Biol 202
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This 0 page Class Notes was uploaded by Natasha on Sunday December 13, 2015. The Class Notes belongs to Biol 202 at St. Cloud State University taught by Schoenfuss, Heiko in Spring 2015. Since its upload, it has received 15 views. For similar materials see Human Anatomy and Physiology I in Biology at St. Cloud State University.
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Date Created: 12/13/15
Biol 202 Lecture 25 and 26 Autonomic Nervous System Autonomic nervous system c The involuntary branch of the nervous system you do not have direct control over it Consists only of motor nerves NO SENSORY NERVES Divided into two divisions o Sympathetic division 0 Parasympathetic division Somatic vs Autonomic System Somatic Autonomic Nerves one motor neuron preganglionic and post ganglionic Effector organs skeletal muscle smoothcardiac muscle glands Neurotransmitters always use acetychoine use acetychoine epinephrine or nonepinephrine Autonomic Functioning Sympathetic ght ight or fright Response to unusual stimulus Takes over to increase activities The E division exercise excitement emergency and embarrassment Anatomy of the sympathetic division Originates from T1L2 Ganglia are at the sympathetic truck 0 Short preganglionic neuron and long postganglionic neuron transmit impulse from CNS to the effector Norepinephrine and epinephrine are neurotransmitters to the effector organ Sympathetic Division 0 A single sympathetic preganglionic ber has many axon collateral and synapses The postganglionic axons typically terminate in several visceral effectors and therefore the effects of the sympathetic stimulation are more widespread than the effects of parasympathetic stimulation Thoracolumbar divisionpreganglionic neurons originate from the thoracic and lumbar levels of the spinal cord Sympathetic ganglia o sympathetic trunk ganglia Located on both sides of the vertebral column Linked by short nerves into sympathetic trunks Joined to ventral rami by white and gray rami communications Fusions of ganglia fewer ganglia than spinal nerves 0 Prevertebral ganglia Unpaired not segmentally arranged Occur only in abdomen and pelvis Lie anterior to the vertebral column Main ganglia celiac superior mesenteric inferior mesenteric aorticorenal and renal The Role of the Adrenal Medulla in the Sympathetic Division 0 Major organ of the sympathetic nervous system Secretes great quantities of epinephrine and a little norepinephrine Stimulated to secrete preganglionic sympathetic bers Postganglionic Neurons in the Sympathetic Division Four ways to innervate An axon may synapse with postganglionic neurons in the ganglion it rst reaches or Sympathetic chains or 0 An axon may continue without synapsing through the sympathetic trunk ganglion to end at a prevertebral ganglion and synapse with postganglionic neurons there or 0 An axon may pass though the sympathetic trunk ganglion and a prevertebral ganglion and then to the adrenal medulla Parasympathetic Division Craniosacral division preganglionic neurons originate from the cranial nerves lll Vll IX and X and sacral spinal nerves SZS4 Parasympathetic ganglia terminal ganglia Presynaptic neuron usually synapses with 45 postsynaptic neurons all of which supply a single visceral effector Cranial Out ow Preganglionic bers run via 0 Oculomotor nerve Ill 0 Facial nerve VII 0 Glossopharyngeal nerve IX 0 Vagus nerve X Fibers innervate visceral organs of the thorax and most of the abdomen Stimulates digestion reduction in heart rate and blood pressure Preganglionic cell bodies 0 Located in dorsal motor nucleus in the medulla Ganglionic neurons Con ned within the walls of organs being innervated Cell bodies located in cranial nerve nuclei in the brain stem Parasympathetic Nervous System Sacral Out ow Emerges from SZS4 lnnervates organs of the pelvis and lower abdomen Preganglionic cell bodies 0 Located in visceral motor region of spinal gray matter 0 Form splanchnic nerves Anatomical Differences in Sympathetic and Parasympathetic Divisions 0 Length of postganglionic bers 0 Sympathetic long 0 Parasympathetic short Branching of axons o Sympathetic axons highly branched In uences many organs 0 Parasympathetic axons few branches Localized effect Neurotransmitters of Autonomic Nervous System Neurotransmitter released by preganglionic axons o Acetylcholine for both branches Neurotransmitter released by postganglionic axons o Sympathetic mostly releases norepinephrine o Parasympathetic release acetylcholine Cholinergic Neurons Cholinergic neurons acetychoine Includes 0 All sympathetic and parasympathetic preganglionic neurons 0 Sympathetic postganglionic neurons that innervate most sweat glands o All parasympathetic postganglionic neurons Autonomic Plexuses A network of sympathetic and parasympathetic axons Cardiac plexus heart Pulmonary plexus the bronchial tree Celiac plexus largest that supplies the stomach spleen pancreas liver gallbladder and adrenal medullae Superior mesenteric plexus small intestine and proximal colon Inferior mesenteric plexus distal colon and rectum Hypogastric plexus urinary bladder and genital organs Renal plexus kidneys and ureters Sacral Parasympathetic Out ow Consists of SZS4 Pelvic splanchnic nerves Physiology of the ANS The ANS maintains homeostasis Autonomic tone a balance between the sympathetic and parasympathetic activity Regulated by hypothalamus The ANS operates without conscious control Sympathetic Responses 0 Stress increases sympathetic system increases ght ight or fright response Increases the production of ATP Dilation of the pupils Increases heart rate and blood pressure Dilation of the airways Constriction of blood vessels that supply the kidneys and gastrointestinal tract 0 Increase blood supply to the skeletal muscles cardia muscle liver and adipose tissue 0 Increase glycogenolysis Increase blood glucose 0 Increase lipolysis Parasympathetic Responses RestandDigest response Conserve and restore body energy Increase digestion and urinary function Decrease body functions that support physical activity Integration and Control of Autonomic Functions 0 Direct innervation brain stem and spinal cord Hypothalamus is the major control and integration center of the ANS It receives input from the limbic system